Optical communications may be carried out over an optical fiber using optical signals processed with orthogonal functions such as Hermite-Gaussian functions and Laguerre-Gaussian functions as described hereinabove in order to improve system bandwidth. Laguerre-Gaussian (LG) and Hermite-Gaussian (HG) signals have three important properties and advantages and one major disadvantage. The advantages include the ability to form two complete families of exact and orthogonal solutions of the paraxial wave equations. Another advantage is that the HG and LG signals are transverse eigenmodes of stable resonators. Finally, the HG and LG signals do not change shape on propagation and provide stable modes of propagation for signals. The disadvantage of HG and LG signals is that the eigenmodes coupled to one another after a long distance of propagation. However, for short distance applications such as intra-data and inter-data center connectivity, and front haul applications or back haul applications, both LG and HG signals provide good solutions within these applications. Thus, there is a need for a manner of transmitting optical signals over a fiber that limits the coupling issues for use with longer distance fiber tranmissions.